Throughout the industrialized world various by-products of manufacturing and other industrial operations have been disposed of by being buried in the earth. Often these buried wastes are sources of air and ground water contamination and pose significant public safety and health risks. In many cases these waste products contain heavy metal compounds which can dissolve in and be carried by ground water. In some instances the waste products contain organic compounds which contaminate ground water. And in some instances the waste products have residual radioactivity. Each of these public safety and health concerns have varying degrees of seriousness depending on the location and composition of the soil in which the wastes are buried.
In some instances, conventional land fill management techniques can be employed to adequately mitigate risks to public health and safety. Simple clay liners and monitoring wells are adequate for many land fills in the world. There are some instances, however, in which health risks are not sufficiently mitigated with conventional land-fill management techniques. There are also instances where wastes have been buried or otherwise disposed of in locations which are not managed as landfills. In these instances and where waste components are particularly toxic, it has been found necessary to remove the waste material and surrounding contaminated soils and move these materials to a remote treatment facility. Obviously, this is a very expensive and cumbersome practice.
In order to reduce the cost of treating soils which are contaminated with highly toxic wastes, various techniques have been devised for in situ treatment of the soil to alter its characteristics and make it less dangerous. One such technique involves heating contaminated soil and other co-mingled buried waste to drive out most organic components as off-gasses. These gasses are collected and incinerated or otherwise treated to mitigate their adverse characteristics. In some instances, the contaminated soil is heated to a high enough temperature to cause melting of the soil. The molten soil and the waste contained therein are then allowed to resolidify into a glassy substance that is more resistant to ground water leaching. Examples of such processes are described in U.S. Pat. No. 5,181,795 (Circeo, Jr. et al.), issued Jan. 26, 1993 and U.S. Pat. No. 4,776,409 (Manchak, Jr. et al.), issued Oct. 11, 1988.
These techniques are suitable for some moderately risky waste deposits. There remains, however, a collection of waste deposits that have been untreatable with any of the techniques that have been heretofore devised.
In some instances the toxic contaminants have migrated to great depths in the earth, in the order of hundreds of feet. Some prior art processes, such as those described in U.S. Pat. No. 4,376,598 (Breans et al.), issued Mar. 15, 1983, initiate melting near the surface of the contaminated soil are not usable to treat contaminated soils at such great depths.
In other instances, the contaminated soil and other buried wastes are composed of materials which, when vitrified, form a substance which is not sufficiently leach resistant. This is particularly significant where the soil contaminants are heavy metals or radioactive substances.
It is desirable therefore to provide a system that will provide for cost effective treatment of waste materials buried in soil of varying composition which will produce a highly leach resistant amalgam of the waste material and the surrounding soil.
It is also desirable to provide a system that is capable of treatment of contaminants which are buried or have migrated to great depths, in the order of hundreds of feet.
Additionally, it is desirable to provide a system that will treat contaminants, particularly radioactive contaminants, without a need to bring any of the contaminants to exposure above ground.